Touch sensitive displays are becoming more and more popular, in particular with handheld mobile devices. Various competing technologies exist. One of these technologies is based on the analysis of acoustic waves travelling in the user interaction interface following or during a touch of the interface by a user. The acoustic waves are sensed by appropriate sensors, e.g. piezoelectric sensors, and the sensed signals are analyzed to determine the position of the touch. This technology is for instance known from FR2841022.
To be able to identify the location of a touch by a user, the sensed signal is typically compared to a set of reference signals. To ensure the repeatability of the analysis across mass produced devices, it is important to acoustically isolate the user interaction surface from its environment. It appeared, however, that it is not easy to integrate the technology into a mass produced product. To be able to determine the touch position in a reliable and precise way, it is necessary to calibrate the algorithm to each product or to work with high integration constraints making the devices expensive.